Zarankiewicz function

Proper noun

 * 1)  The function for which the Zarankiewicz problem seeks a formula: ​z(m, n; s, t), denoting the largest possible number of edges in a bipartite graph G = (U, V, E) for which |U| = m and |V| = n, but which does not contain a subgraph of the form Ks,t.